1. Field of the Invention
This invention relates to optical image scanning systems and, more particularly, to such systems utilizing fiber optic coupling arrays.
2. Description of the Prior Art
Image scanners have long been known in the prior art. For example, the Nipkow disc, invented in 1884, was used in electromechanical precursors of the modern television system.
The field of fiber optics is now well established, and a variety of fiber optic scanning devices have been developed. Examples of fiber optic scanning apparatus may be found in the disclosures of the Goldhammer et al U.S. Pat. Nos. 3,401,232 and 3,325,594 and in other U.S. Pat. Nos. to Ressler, 3,192,391; Strickholm, 3,167,612; Day, 3,036,153; Trott, 3,210,462; Kapany et al, 3,255,357; Cannella, 3,365,580; and Hicks, Jr., 3,240,106. The Trott patent, beginning at Col. 2, line 37, contains a good summary description of the properties of optical fibers and the use of fiber bundles or arrays for optical scanning. Singer, Jr. in U.S. Pat. No. 3,272,063 discloses a particular device which is useful in the preparation and handling of optical fiber bundles.
The present invention employs to particular advantage in an optical scanning system an integral array of substantially identical, fiber optic couplers. These couplers are of the unidirectional type, referred to as launch couplers, disclosed for example in my U.S. Pat. No. 4,307,933 entitled OPTICAL FIBER LAUNCH COUPLER, of which I am named as inventor with Phillip B. Ward, Jr. The fabrication of an array of such launch couplers is disclosed in U.S. application Ser. No. 333,955 filed Dec. 23, 1981, entitled FIBER OPTIC COUPLER ARRAY AND FABRICATION METHOD of John P. Palmer and Phillip B. Ward, Jr., assigned to the assignee of this invention. The disclosure of that application is incorporated herein by reference. In brief, an array of substantially identical launch couplers is fabricated by preparing first and second support blocks with pluralities of parallel grooves and placing appropriate optical fibers in the grooves. Each launch coupler comprises a launch fiber and a throughput fiber. Epoxy resin is applied to embed the respective fibers in their blocks and then the resin and embedded fibers are lapped to develop opposed mating planar surfaces. The launch fibers are lapped entirely through the cores to expose severed end surfaces of generally elliptical shape. The throughput fibers are lapped only deep enough to expose a corresponding surface of like extent and dimensions. The two blocks are then joined at the planar surfaces, and the array of launch couplers is aligned while applying light signals to the input ports of two launch fibers at opposite ends of the array and monitoring the light output at the output ports of the corresponding throughput fibers until the output is maximized. Preferred apparatus for use in the alignment procedure is disclosed in U.S. Pat. No. 4,302,267 entitled OPTICAL FIBER MATING APPARATUS AND METHOD of Palmer and Ward. Afterward the two blocks are affixed to each other by epoxy resin or other suitable adhesive. An array of launch couplers fabricated in this fashion can be used as the basis of an optical scanning system.